peterson



3 Sheets-Sheet 1 Jan. 21, 1964 R. H. PETERSON ELECTRONIC ORGAN Original Filed May 16. 1958 JPG/61m?! 85C/tard# Pefsor? MMM vwl Q55 @dwf-Rey Jan. 2l, 1964 R. H. PETERSON ELECTRONIC oRGAN 3 Sheets-Sheet 2 Original Filed May 1S. 1958 I r1 fe I'CGY ,elle/'card #Peterson Jan- 21. 1964 R. H. PETERSON ELECTRONIC ORGAN 3 Sheets-Sheet 3 Original Filed May 16, 1958 AMPLITUDE United States Patent O 25,515 ELECTRUNIC RGAN Richard H. Peterson, Oak Lawn, lll.

Original No. 3,033,365, dated .lune 12, 1962, Ser. No. 735,854, May 16, 1958. Application for reissue July 2t?, 1962, Ser. No. 213,568

22 Claims. (Cl. 84`-1.26)

Matter enclosed in heavy brackets [1 appears in the original patent but forms n part of this reissue specilication; matter printed in italics indicates the additions made by reissue.

My invention relates to electronic musical instruments of the organ type. It includes among its objects and advantages a transistor oscillator capable of extremely prolonged decay without undesirable transistory sound effects. It also includes player-controlled percussion fleets variable over a wide range. It also includes the peculiar transistory percussion eilcct commonly produced by piano strings or by chime bars equipped with felt dampcrs. Further objects and advantages will become apparent as the description proceeds.

FIGURE 1 is a schematic wiring diagram of an oscillator and accessories according to the invention;

FlGURE Z is a perspective View of a complete organ with theA front panel removed;

FIGURE 3 is a similar View of the rear side only of the same organ;

FlGURE 4 is a diagram indicating various decay characteristics; and

FIGURE 5 is a diagram of a multiple stop switch.

in the embodiment selected to illustrate the invention, the organ itself may comprise a conventional console having a solo manual 1Q, and accompaniment manual 12, and a pedal board 14, assembled in a conventional geometrical relationship. There is also an expression control pedal 16 and a tremolo rotor 18. Behind the pedal board 14, Ihave indicated twelve different tone generator chasses 26. The chasses illustrated is according to my copcnding application, S.N. 598,582, filed July 18, 1956, now Patent Number 2,924,784. Due to the exceptionally small volume occupied, it is possible to house seventy-two oscillators assembled in twelve groups of six eacih within the shallow space occupying about 32 percent of the rear side of the casing and about percent of the depth of the casing, behind the pedal board 14.

This extreme reduction in the volume occupied makes it possible to include within the contines of a conventional spinet body, not only the entire generator equipment,

and electronic accessories, but an entire loud speaker '78 and an enclosure St? for it for securing the correct acoustics, and a trcmolo rotor 18 for delivering the sound. in FJURE 3, there is also indicated the location of the power amplifier 19, and the percussion unit 28.

itelerring now to FIGURE l, it is convenient to discuss the wiring shown in four subdivisions, comprising the amplifier unit 22, the oscillator 24, the manual control 26, and the unit 2S. This unit 28 provides unique and desirable percussion and reverberation cflccts. it is hereinafter identified, for brevity only, as the percussion unit. There is also a power source 3() provided with a plurality of voltage taps 32. ln this specific embodiment, the source may receive 60 cycle alternating current through supply cables 34 and deliver predetermined selected D C. potential, as selected from time to time by the player, to the various terminals and buses of the entire organ. The voltages employed in practice at present vary in stops of `three volts each from plus 3 volts to minus 27 volts. As the details of transforming 120 volts 60 cycle AC. into D.C. at Various voltages are Well known in the art and may be conventional, this description is not cncumbered therewith.

Reissued Jan. 2l, 1964 ice The transistor 35 is iof the PNP type usually employed for audio-frequency work. lt has a base connection at 36, an emitter connection at 38, and a collector connection at 4t). The connection 36 and 38 are part ol` an exciting loop running from the base 36 through a base resistor 42, a base capacitor 44, a minor upper fraction 46 ot the winding 48, and an emitter resistor E() back to the emitter 33.

The winding 48 is physically associated with a ferromagnetic core 52 of ceramic material, as described in my co-pending application, S.N. 598,582, filed July 18, 1956, now Patent Number 2,924,784. The oscillating loop proper, or tank circuit, is completed by the capacitor 55 connected across the ends of the winding 48, and the entire loop is grounded at 54. 1t will be noted that thc exciting circuit subdivides the winding 48 into an upper minor fraction 46 and a lower major fraction 56.

To energize the exciting circuit, potential is delivered from point 58 through resistor 6tl to point 62 and from there through a resistor 64 of low impedance to the collector 40. The same potential from the point 62 is also connected through a resistor 66 oi 33,60() ohms to the base 36.

The point 62 is also connected through a capacitor 68 to ground. It will be apparent that thc resistor 6l) and the capacitor 68 are an RC time-delay circuit tending to control the time-potential curve for the point 62 when the potential is first delivered to the point 58. During the building up of the oscillation, a minor iniluence on the potential of the point 62 is exerted bythe oscillator itself.

The hase capacitor 44 is also charging through the following circuits: (l) portion 46 of the inductor winding 43; (2) resistor 50'; (3) a split circuit of which one branch is the transistor from emitter to base, and the other branch is the transistor from emitter to collector and resistors 64 and 66; (4) base resistor 42. However, the charging of capacitor 44 is relatively slow and its effect in lowering the potential at point 62 relatively slight, so that the potential of the point 62 rises at a rate determined almost entirely by capacitor 68 and resistor 60. Because of this relationship, there will be one time-potential curve for the collector 4d and a different time-potential curve for the base 36.

When the energy supply to point 58 is interrupted, as by opening the key switch, resistor 6l) is left unconnected at its lower end and no longer performs any function. But the charge on capacitor 68 has to nd its way to ground at 54 entirely through resistor 64, the transistor, collector to emitter, resistor Si), and the lower major segment 56 of the winding 48. The impedance of this path is much greater than that of resistor 60, and, accordingly, the decay of working potential in the exciting circuit will be relatively slow, and the decay of the oscillation will be much longer than the attack period. Except for abnormally staccato music, this relationship between attack and decay is esthetically preferable.

At the same time that capacitor 63 is discharging, as above outlined, capacitor 44 is discharging through a different network having certain portions in common with the discharge path of capacitor 68. Capacitor 44 discharges through the same path through which it charged during attack, but its timediscliargc curve will not he the same as its time-charge curve because the competing potential drop in those portions of its circuit that must also discharge capacitor 68 will be ditlerent during attack and during decay. Therefore, during decay, the tiniepotential curve for the collector and the time-potential curve for the base will be materially different, and neither' of them will be the counterpart of the same potentials during attack.

From the point 7l) of the oscillator, signal is delivered through rr, istor 72 to an assembly bus 74 connected to receive signal from all the oscillators. The amplifier unit 22 includes an amplifier proper 76 receiving signal from the bus Ti. lt may also receive signal from a plurality ot" additional buses which may be those described in detail in Patent 2,649,006. The amplifier includes playercontrolled expression means for varying the gain ratio, which may be according to Patent 2,712,040, operating under the control of the expression control pedal 16.

The amplilier delivers the composite signal from the bus har 74. after amplification, to a loud-speaker 78. The loud-speaker 73 opens downwardly through an opening in the bottom of the speaker enclosure 80, and the resultant sound issues from the tremolo rotor through sound outlets at $2 and 34 in the organ casing. If the rotor 18 is stationary, a constant tone will be delivered. li the rotor is rotated by means of the motor 84, the Doppler cliect described in U.S. Reissue Patent 23,323 will change the constant sound emanating from the loud-speaker to give it a slightly variable frequency, and a slight variation in intensity. with the ultimate effect of a most pleasant and natural vibrato.

VARIABLE PERCUSSION The prolonged decay, characteristic of chimes, harps, glockenspiels, and instruments of the same general class, is frequently desired only on the solo manual.

Referring to FlGURE l, point 58 receives potential from any one or more ot` three key switches, a solo key switch S6. an accompaniment key switch 88, and a pedal key switch 99. Each of these switches is connected to th point 58 through a rectifier' diode 92. Thus, when more than one of the key switches 86, 88, and 90 are closed, the switch delivering the greatest potential will control the potential of point 58, so long as that switch remains closed. It" the switch of greater potential is opened while a switch of lesser potential is still closed, the amplitude of oscillation will decay back to a lesser intensity, but the oscillator will continue to deliver signal without interruption.

Solo key switch 86 is connected through the on-and-otf stop switch 94 with the percussion unit 28, as by means of a player-controlled stop element 97 (see FIGURE 2).

Capacitor 9S functions to prolong the decay of the tone, as toll ws: The charging of capacitor 98 draws current through two circuits. One circuit includes resistor 104 and 106. The other is through the oscillator as follows: Resistor 60, a divided portion from energizing terminal 62 to the emitter resistor 50 and section 56 of winding 4S to ground at S-l. The divided portion between 62 and 38 has one path through resistor 6d and the transistor, hase, to emitter; and a parallel path through resistor 54 and the transistor, collector to emitter. The impedance oi resistor' ll is many times that of the oscillator network, so that nearly all the charging current for the capacitor 9S co cs through the `cscillator circuit and is therefore ctlective to prolong the oscillation of the oscillator after th ph 'ing key is moved to open position. This continued "ticn is of decreasing amplitude and the tone dimin- 5 accordingly. This diminution of tone is commonly referred to as the decay or" the tone.

To enable the player to select a variety of. decay rates at will. .it would be possible to provide several sets of nce." 1H, with a multiple gang switch for each of tl sets o-l" resistors, as disclosed in my tto-pending application. SN. Suoni-t6, tiled February 20, 1956, now Patent Number 2.924,13?. According to the present invention, a sm le additional set of resistors 168 provides a plurality o? dii'erent d" 'ty rates und at the same time secures an litional d: t'ole esthetic eifect.

.isocissctl with the capacitor 93 is another charging circuit eflectively in parallel with the oscillator charging circuit.

This snubbing circuit is for the purpose of conthe rate of dsc-.1y by providing a means for charging capacitor 93 more quickly than would be possible Ail) if all the charging current had to come through the oscillator circuit, (plus a minor fraction coming through resistor illu). lt is desirable to have the snuobing circuit eileetive in varying degrees at the will oi the operator to control the length oi the decay period throughout a range extending from a small fraction of a second up to about three seconds or more.

The snubbing circuit for each oscillator includes a one thousand ohm resistor 10S and a diode 11B. These are connected in series with each other' and between the snubbing bus 112 and the side of capacitor 9S remote from the keying voltage. The snubbing bus 112 may be connected by the operator to any selected potential available in the power source 3) by means of a selector switch 93.

The selector 93 determines the selected potential for bus 112, and the grounded resistor 106 completes the circuit back to the power pack 30. lt will be understoot that there are as many percussion units 28, as there are notes for which percussion effects are desired, and that the bus bar 112 is connected to a multiplicity of percussion units.

The keying voltage at 86 may be varied between minus 3 and minus 9 volts and when the key switch is closed, the potential of the conductor 91 will be the keying voltage. When the key switch 86 is moved to open position, this voltage `will decrease gradually to zero volts. During most of the time of this decrease, the tone will decrease accordingly, and, shortly before the voltage becomes Zero, the oscillator will discontinue oscillation and sound `will cease. Assuming a keying voltage ol minus 9, if the snubbing bus 112 is also at minus 9 volts, the Voltage across diode 11E) can never be of polarity to cause the diode to conduct. Under these conditions, the capacitor 98 must charge entirely through the oscillator circuit and through resistor 106, and this will result in a maximum period of attenuation.

However, if the voltage on the snubbing bus is changed to Zero, or to a ysmall plus value, the diode will remain conductive until the capacitor 98 is completely charged, and the ordinary decay period will be accelerated in a ratio of about ten to one.

lf the voltage of the snubbing bus 112 is made minus six, or minus three, or any negative value less than the keying voltage of minus nine, the diode 110 will remain conductive until the potential of conductor 91 has reached the potential of snubbing bus itil. and the remainder ot' the decay will take place at the slower rate required by charging through the oscillator and through resistor ihn'. This results in a total time of decay intermediate between the minimum and the maximum. But this intermediate total decay time will comprise a first portion during which the decay is relatively rapid, and a later portion during which the decay is relatively slow. The two-stage decay characteristic just described is remarkably similar to that oi chime bars, or the like, with felt dampers, and to that of a piano when played without the sustain pedal.

Because the pedal tones are played with the foot, there is likely to be a time interval between the time that one pedal key is released and the next one depressed. This frequently causes an undesirable lack or continuity in the music. Because the most advantageous decay period for the pedal notes is usually ditlercnt from that desired for the solo notes, l provide a separate pedal sustaining capacitor 99 connected in series with resistor 165 and gang switches 95, between ground and thc terminal of lLey switch 9@ remote from the power source. Lil-:e capacitor 68, capacitor @El is connected in parallel with the oscillator, whereas capacitor 13 is connected in series. The equivalent snubbing circuit comprises an additional. separate snubbing bus 113 connected through resistor lili? and dio-de .lil to the conductor M3. It will be obvious that by keeping the snubbing bus 113 at various selected potentials, effects completely' analogous with those secured by the snubbing bus 112 are available to the player.

Each of the three time-delay capacitors 68, 93, and 99 can obviously be connected either in series with the oscillator or in parallel with it. The only difference is in the polarity of the capacitor and a capacitor connected in series will be charged when the oscillator is not oscillating and discharged while the oscillator functions, While a capacitor connected in parallel will remain continuously discharged when the oscillator is not oscillating, and be charged when the note is played. I provide also a stop switch 95 for disconnecting capacitor 99 completely, in the same way that stop switch 94 disconnects capacitor 98.

Referring now to FIGURE 4, the diagram indicates graphically one set of time-volume characteristics that may be at the disposal of the player. Time is shown as a horizontal dimension and amplitude as a vertical, and the horizontal line at 114 indicates the intensity ofthe sustained note obtained on the solo manual wih a playing voltage of minus nine. The smooth curve 116 indicates the effect when the bus bar 112 is also at minus nine. This produces the esthetic effect of a carillon, or the like.

With the bus bar at minus six volts, a curve results having a relatively steep portion ending at 118 and a less `inclined portion from 118 to extinction. This may be made to produce a surprisingly accurate illusion of the effect of an organ played in a very large auditorium, where the auditorium itself creates a reverberation equivaient to the decay indicated. Because the diode 110 changes from conductive to non-conductive over a small voltage range, rather than at a precise voltage, the curve at 118 does not come to a sharp point.

With the bus at minus three, the curve is steep down to a lower intensity at point 120, and then less inclined down to extinction. This effect may be made to coincide with that of a piano played without the sustain pedal in a room of ordinary size.

With the bus bar at a voltage of zero, the result is curve 122, which is almost, but not absolutely, identical with that secured when the gang switch 94 is open, and the percussion unit is not functioning.

With the bus bar at plus one volt, the curve 124 results, and this produces a staccato decay characteristic. which will be rendered more striking with the bus bar at plus three or four volts.

ln addition, the bus bar 112. may be in multiple, with the range of the instrument sub-divided between the different bus bars, and an upper octave of oscillators may have one decay characteristic; the next octave a different one, and so on. The following table shows one desirable assortment of values:

These values relate to the duration of the decay period only, and have nothing to do with tone quality, which is controlled in other ways.

ln the piano, as in certain other instruments, the lower notes have a longer decay period than the higher ones. The bottom line oi the table indicates how these peculiar and desirable tonal characteristics can be closely duplicated electronically.

One set oi suitable working values for the components of a transistor osciilator and percussion unit according to the invention is as follows for the note A3 with a frequency of 440 cycles per second.

6 TABLE on VALUES Resistor 42 0 to 1,000 ohms. Resistance of winding 48 48 ohms. Resistor 50 220 ohms. Resistor 66 33,000 ohms. Resistor 64 O to 1,000 ohms. Resistor 60 330 ohms. Capacitor 44 5 mid.

Capacitor 53 0.95 mfd. Capacitor 68 l0 mfd. Capacitor 98 200 mfd. Capacitor 99 200 mfd. Resistors 104 and 105 22 ohms. Resistors 108 and 109 1,000 ohms. Resistor 106 10,000 ohms. lnduetance 48, 52 0.145 henrys.

Resistors 42 and 64 are at zero in present practice, but values up to 1,000 ohms can be used at these points to secure variations in attack and decay characteristics.

The values of capacitor 53 and inductance 46, 52 are approximate only. The core 52 is adjustable to secure exact tuning.

In the execution of complicated organ music, and in many other types of expert musical performances, the things that the player needs to accomplish almost instantly by a touch of the foot or linger, include a wide variety of relatively complicated adjustments.

Among the more necessary of such complex adjustments is the adjustment of the relative loudness of the notes played on the solo manual and the notes played on the accompaniment manual and the notes played on the pedal clavier. It will be obvious that the subject matter already disclosed enables an operator to sound one of the relatively low notes with any one or more of the three sets of key switches. At a given instant, such a note may be connected to receive energizing potential through all three switches 86, 88, and 90, and at such an instant the volume will be the relatively high volume due to the relatively high energizing voltage available through the key switch 90. Under such circumstances, if the key switch is opened while the other two switches remain closed, the intensity of the tone will decay back to a lower intensity, which will be the intensity secured by the key switch E6. A fraction of a second later, the key switch 86 may open because the solo air has shifted to another note, whereupon the intensity will decay further to that corresponding to the voltage available from the key 88. And finally, if the key 88 is opened, there will be a different decay characteristic in the dying away of the sound extinction.

This and many other sequences of varying intensity result automatically from mere manipulation of the keys by the operator, so long as a predetermined relative intensity for cach of the different sets of key switches is appropriate to the requirement of the musical piece. But, when the operator needs to change from very loud notes on the pedal clavier to notes of normal loudness, or to emphasize a passage played in chords with the key switches S3, while the key switches 86 play a faint obligato, the relative potentials of the different banks of key switches need to be shifted substantially in the flick of an eye-lash.

Referring now to FIGURES 2 and 5, I have indicated balancer switch means at comprising a knurled knob 126. A contact member 12S connected to the key switches S6 and another contact member 130 connected to the key switches SS are indicated as rigid with the knob 126 and rotatable therewith. In the position of FIGURE 5, contact 128 is riding on a sector 132 carrying a potential of minus 9 received from the potential `box through a conductor 133 and contact 130 is receiving the same voltage from sector 134 connected to the same conductor 133. On the right side above the sector 132, I provide a short sector 136 carrying a potential of minus 6 and above that a short sector 140 carrying a potential of minus 3. Similarly, on the left side, the rst sector above the Sector 134 is sector 138 carrying a potential of minus 6 and above that is sector 142 carrying a. potential of minus 3.

It will be obvious that counter-clockwise rotation of thc button 126 will move contact 12S across from sector 132 to 136. and in a second step from sector 136 to litt?. This will reduce the potential of the switch keys 86 in two successive steps while the contact for switch keys 88 merely slides down along the long sector 134 and continues to receive minus 9 volts. Similarly', clockwise rotation of the same button will keep the contact 128 in engagement with the long sector 132 while the Contact 139 moves up to receive only minus 6 volts from sector 138 and in a second step to receive only minus 3 volts from sector 142.

l thus provide tive different relative intensity ratios between switch keys 86 and 88. in the position ot FIG- URE 5 'eys 86 and 88 deliver the same intensity. Cloco wise movement to engage sector 138 will reduce the accompaniment intensity to that resulting from two thirds of the solo manual voltage and further movement to sector 142 will reduce the accompaniment to the intensity resulting from one third of the solo manual voltage, mal:- ing it seem like a mere background echo. Counter-clockwise rotation to engage sector 136 will relegato the solo air to a background, and movement to sector 140 will make the solo switches 86 deliver a mere echo compared with switches 83.

lf this change in ratio were only change in actual volume, the capacity of the instrument would be relatively inadequate. But the foot pedal 16 controls the amplifier 76. and superimposes a total control on the actual loudness of everything that is received by the amplifier, and the expert organist is able to have instant control ol" s trom one musical passage to the nett throughout the entire range necessary for the performance of complicated music.

Because these adjustments of relative intensity originate in the signal from oscillators themselves, it is possible to make a complete and satisfactory musical instrument with a single set of oscillators, whereas it was previously considered necessary to have separate banks of oscillators to secure the same variety in the musical ettcct.

Finally, the stop switch E17, when closed merely changes the decay rate of the notes played on the pedal clavier, but a touch oi the linger enables the player to have four ditlcrent intensities for the switch keys 9i). Besides the stop tablet 95 (see FIGURE 2) is a duplicate stop tablet 144 labeled soft` another tablet 1% labeled medium, and another tablet 148 labeled loud. With all three tablets horizontal and undisturbed, the clavier notes will be as soft as is ever desired when clavier notes are to be played at all. A tap or the finger to tilt up stop 144 will increase this intensity materially and tablets 146 and 14S provide two more steps of increasing intensity. It should be emphasized also that these bass notes are only adjusted in volume as a matter of intensity ratio between thrtn atri the notcs emanating from the other two key boards., w the merged totality is still controlled to have acoustic intensity the player desires by means of the pedal if. lite mfr, crial employed in the core EQ is that disclosed in my tio-pending application, SN. 598,582, tiled July i8, i956, now Patent Number 2,924,784. Many of these ceramic magnet materials are well known in the art, and, per se. torni no part of my invention. As distinguished from metallic magnet cores, most oi them have the peculiar clic. teristics required for this service, but only over a minor action ot their normal range ol' flux densities, l ch minor fraction occupies approximately the lower thml of the flux density range. Ey keeping the maximum flux dens y of the core 52 down within this abnormally low limit, all three ofthe desired characteristics are made possible.

It has been pointed. out that the time-potential curves .for the base 3o, tle emitter 40, and the collector 38 are specically diliercnt from each other during attack, and that during decay a diltcrent curve obtains for each of thrA n, the tnrec decay curves being also dillerent from each other. tl/ith some of the longer decay periods, the relationship between the three potentials tends to approach an inoperative condition. such that oscillation is interrupted lor a very short time, and then resumed. This hiatus sounds lilie nothing less than an ordinary hiecup, or burp, and would be h'y lj objectionable. Control in this respect is by varying the value of resistor 5t). It the value is too lont', the burp appears, and it' it is too high, the attack becomes stu eish. For this reason` it may be desirallle to maite t sister 50 adjustable for ease in manufacture. as by means of the Contact adjustment indicated at 51 in FlGUltli l.

thers ma i' readily adapt the invention for use under various conditions ot "vice by employing one or more of tbc novel features d .closed or equivalents thereof. As at pescnt advised, with respect to the apparent scope of my invention, I desire to claim the following subject matter:

1. ln an electronic organ of the type comprising, in combination: a loud speaker; a series of oscillators operatively connected to activate said loud speaker; each oscillator being responsive to D.C. energizing voltage and having a frequency equal to that oi a desired musical tone; the amplitude of oscillator response at ditlerent energizing voltages being a smooth and continuous function of the energizing voltage, from maximum values substantially down to inaudibility; the amplitude oi loud speaker response being a function of the amplitude of oscillator response; the frequency oi" each oscillator being constant without variation noticeable to the ear, from maximum loudness substantially down to inaudibility; a player-controlled 1rrey switch for each oscillator for delivering energizing potential to said oscillator only as long as the player holds the key down; said oscillator being normally not in oscillation during playing of the organ and requiring a time interval to build up its oscillation upon receipt of energizing potential: said time interval for build-up being of the order ot' magnitude ot the attack time for a windblown musical instrument; the combination of: a rst timing capacitor adapted to be in a selected one of two condition charged and discharged; connections rendered operative ty cha 'ing the position of said key switch for changing the condiLon of said capacitor to one condition unon closure of said lrey switch: connections .for changing the cond' 'on back to the orig tal condition upon opening ot" said ...,y switch; said lirst timing capacitor being connected to return to open-key condition, when said key switch is moved from closed to open position, by current in a first circuit passing through said oscillator unit, thus prolonging the decay oi said unit; a second, independent circuit tor accelerating the restoration of the openkey condition when said ltey switch is moved from closed to open position; said second circuit maintaining said timing capacitor in opendt'cy condition when said ltcy switch nains in open position; a bus bar; bus connections from sont bus bar to one terminal oi cach of a plurality oit said timing capacitors; a diode in each of said bus connections arranged to permit current flow only in the direction to restore open-:lacy condition; resistance in series with each diode for determining the spec/l with which bus-bar potential restores open-key condition; a first player-controlled stop switch means adapted to remain continuously in any selected position until re-adjustcd by the player; and connections between said stop switch means and said bus bar ior rendering said bus bar operative or inoperative.

2. A combination according to claim Ll in which said irst player-controlled stop switch means includes connections for varying the potential of said bus bar.

3. A combination according to claim 2 in which said 9 lirst player-controlled stop switch means is in multiple and comprises a multiple-position switch adapted to transmit any one of a plurality of predetermined voltages t said bus bar, and an on-and-otl switch controlling the 0perativeness or inoperativeness of said multiple position switch and said bus bar.

4. A combination according to claim 1 in which said bus bar restores open-key condition more rapidly than current through said oscillator; said bus bar being adjustable to voltages intermediate between playing voltage and zero; whereby, at intermediate bus-bar voltages, the decay is relatively rapid down to an intermediate intensity and then less rapid down to extinction,

5. A combination according to claim 1 in which said oscillator is an LC transistor oscillator employing D.C. voltages up to about 27 volts, and said bus bar is adjustable to D.C. potentials from playing voltage to zero.

6. A combination according to claim 5 in which said bus bar is also adjustable to reversed voltage; whereby the entire decay period can be reduced to a shorter time than the inherent decay rate of the oscillator when used without said timing capacitor.

7. A combination according to claim 1 in which said oscillator unit includes an RC time delay circuit between said key switch and the oscillator proper; said RC delay circuit including a second timing capacitor smaller than said first mentioned timing capacitor; a circuit for changing the condition of said second timing capacitor when said key is moved from open position to closed position over a time interval corresponding to the normal attack period of an acoustical musical instrument of the same frequency; the resistor of said RC delay circuit having an impedance much lower than the oscillator; said second timing capacitor returning to open-key condition by current through said oscillator; whereby said second timing capacitor produces a normal decay period greater than the normal attack period, but less than the decay period obtainable with said first timing capacitor.

8. A combination according to claim 7 in which one of said timing capacitors is connected in parallel With said oscillator and is in charged condition when said playing key is in closed position; and the other of said timing capacitors is connected in series with said oscillator and is in discharged condition when said playing key is in closed position.

9. A combination according to claim 8 in which said second, smaller timing capacitor is connected in parallel with said oscillator and said first, larger capacitor is connected in series.

10. A combination according to claim 2 in which said bus bar is subdivided into a plurality of separate sections; said first player-controlled stop switch means being Connected to supply independently predetermined voltages to each of the different sections of said bus bar.

11. A combination according to claim 10 in which the predetermined voltages for the bus bar sections for groups of notes of lower frequency are adjusted to produce longer decay periods than for groups of notes of higher frequeney.

12. A combination according to claim 1 in combination with a second player-controlled stop switch means for delivering potentials to said key switches.

13. A combination according to claim l2 in combination with a second duplicate set of key switches; and a third player-controlled stop switch means for delivering different potentials to said second set of key switches.

14. A combination according to claim 13 in which said second and third player controlled stop switch means are mechanically interconnected to permit both sets of key switches to receive the same maximum voltage, or to reduce the voltage for either set but not both.

15. A combination according to claim 13 in combination with a third set of key switches for only a portion of said oscillators of relatively low frequencies; and a fourth player-controlled stop Switch means for delivering different potentials to said third set of key switches.

16. A combination according to claim 15 in which each oscillator within the range of said third set of key switches, is provided with a third timing capacitor; and a third timing capacitor circuit controlled by the key switch of said third set of key switches; and a iifth playercontrolled stop switch means for rendering said third timing capacitors operative or inoperative.

17. In an electronic organ, in combination: an oscillator characterized by constant frequency over a wide range of amplitudes; a potential source; a lirst playercontrolled key-switch means for initiating and interrupting the delivery of potential from said source to said oscillator; electrical energy storage means adapted to assume a pre-selected one of two conditions, identiiied as charged and discharged; automatic means for changing the condition of said storage means in one direction when delivery is initiated, and in the opposite direction when delivery is interrupted; said automatic means comprising connections for changing the storage condition as a predetermined function of time by energy direct from said source when delivery is initiated, and connections for changing it back as a different predetermined basic function of time when delivery is interrupted, by energy passing also through said oscillator and activating said oscillator; a second separately controllable player-controlled stop means for speeding up only an initial predetermined portion of the change after interruption, to shorten said basic time function; and translating means for generating musical sound corresponding in intensity to the oscillations of said oscillator.

18. A combination according to claim 17 in combination with a third, separately controllable, player-controlled stop means for varying the size of said predetermined portion of accelerated change.

19. A combination according` to claim 18, in which said third player-controlled stop means is a bus bar; accelerated change means connected with said bus bar and activated by the difference between bus bar potential and storage potential; and a player-controlled stop for connecting said bus bar to a selected one of a plurality of different potentials.

2C). A combination according to claim 1S, in combination with a fourth, separately controllable. player-ccntrolled stop means for adjusting the basic time function after interruption to any selected one of a pluarlity of different values.

211. A combination according to claim 2d. in whic. said fourth stop means is adapted to change the time function by changing the amount of energy stored in said storage means.

22. ln an electronic musical instrument, iu combination: a series of signal sources timed to flu' notes of the nuls-ical seule; cuela source having n control terminal and being adapted to deliver output sig/url lmrilig nu wnplirmlr wlzclz is a function of Ilia polclzliul of .und r'rmium'; n source of DC. activating potential; a playing ltry operotivcly Connected with enc/1 control terminal und ultli .will DC. .rom-ce, for changing the potential of .ro-icl terminal from an Original ifmflire potential :o full activating porcatiul; electric-al energy storage minus courier-fell to carla control terminal; mul o restoring circuit connector! ro @dell Control terminal for reim/:ing soir] termino! to i11- reclive potential u'lirn potentiel from .Stoll Df. :more is withdrawn.' .raid restoring circuit including r.' :leroy circuit Connected to cat-lr control fzl'mlirfl, which no1-molly rrtnrfrs sold terminal Io inactive potential in a prerlefcrrm'necl period of time; and additional mmm' coilnrrml lo .'.tflrl decay circuit for speeding lip tlm decoy tlouli lo o ,amuletermlnerl intermediate potential.

(References on following page) Refereznees Cited in the lc of this patent or the original patent UNITED STATES PATENTS Hammond Oct. 1, 1940 Swuhrlcl; Nov. 26. 1940 Weathers et al June 2, 1912 Tmub Sept. 15, 194.2 Hammond et al July 6, 1943 Zuck Sept. 6, 1949 10 

